利用常规观测资料、地面加密观测资料、逐时云顶亮温TBB资料和1°×1°NCEP/NCAR再分析资料,对2010年7月24—25日四川盆地暴雨天气过程中尺度对流系统发生、发展的物理量特征和动力机制进行了分析。结果表明:(1)此次四川盆地西部区域性暴雨天气过程是由中—β尺度云团合并、加强所生成的中—α尺度对流系统造成的。(2)散度、涡度、垂直速度和相当位温的分布与对流系统的发生、发展较一致,特别是在中—α尺度对流系统强烈发展阶段有很好的对应关系,为中—α尺度对流系统的发生、发展提供了有利的动力和热力条件。(3)大气非平衡强迫对发生在四川盆地西部的区域性暴雨有较好的指示意义,是激发暴雨天气的动力机制。(4)暴雨发生期间降水造成的非绝热加热有利于强降水天气的维持。
Using of the routine observational, surface intensive observation, FY-2D satellite and NCEP/NCAR l°×1°reanalysis data, the meso-α scale convective system in a rainstorm event of Sichuan basin from 24 to 25 July 2010 is analyzed. The obtained result are as follows: (1) The rainstorm process is produced by a meso-α scale convective system generated by the mergence of the meso-β scale convective system. (2) The distributions of the divergence, vorticity, vertical velocity and the equivalent potential temperature are consistent with the occurrence and development of the meso-β scale convective system, especially at the developmental stage of the meso-a scale convective system, which provide the enough dynamic and thermodynamic conditions for the occurrence and development of mesoscale convective system. (3) The barotropic non-equilibrium force is a good indication to the regional rainstorm in western Sichuan basin, which is the excited mechanism of rainstorm. (4) The diabatie heating released by the rainstorm condensation plays a feedback role in the maintenance of rainstorm.